Working fluid for a compression refrigeration system



Patented May 8, 1951 WORKING FLUID FOR, A COlWPRESSION REFRIGERATIONSYSTEM Alfred E. Bishop,

Oakwood, and Stanley V. Cook,

Dayton, Ohio, assignors to General Motors Corporation, Delaware Dayton,Ohio, a corporation of No Drawing. Application September 21, 1946,

Serial No. 698,428

' This invention relates to chemistry and more particularly to a workingfluid for use in refrigcrating systems.

In refrigerating systems employing a halogenated hydrocarbon as therefrigerant, slight traces of corrosion and copper plating have beendiscovered. It is believed this corrosion is due to slight traces ofsuch end products as water and hydrochloric acid probably formed by theslow break-down of the refrigerant at temperatures occurring on the hightemperature side of the system. The presence of water, is alsoobjectionable in that it may result in the formation of ice crystals onthe cold or low pressure side of the system.

To overcome this latter objection it has been the custom to add to thelubricant and the refrigerant a small amount of an antifreeze such asmethyl alcohol. It has been found, however, that the addition of suchantifreeze increases the corrosive and copper plating action takingplace withinthe system. D V j It is the object of our invention toprovide a working fluid which includes in addition to the halogenatedhydrocarbon refrigerant and lubricant either with or without theantifreeze, one or more organic oxides of the epoxy type acting as aninhibitor or stabilizer whereby thecorrosive and copper plating actionsare substantially eliminated.

As one specific example of our invention, we employ as a refrigerantdifluorodichloro methane. As a lubricant, we employ mineral oil. Theamount of refrigerant and the amount of the mineral oil varies with theparticular refrigerating system in which the working fluid is to beused. For example, the amount of lubricant required will vary accordingto the amount of lubricant space provided in the compressor as well asto the efiiciency of the separation of the lubricant from therefrigerant after compression and to the dependability and effectivenessof the return of the lubricant from the other parts of the system to thecompressor. In general, the amount of lubricant will vary betweenone-fifth and an amount equal to the refrigerant by weight, dependingupon the characteristics of the system wherein it is to be used. When noalcohol is to be used in the system, we include propylene oxide 1,2 inthe amount of to 5% of the refrigerant.

Where alcohol is to be used, we prefer to use methyl alcohol. In thisevent, the alcohol may be in the proportion of nine times the amount ofthe propylene oxide 1,2 but a greater propor- 7 Claims. (01. 252 68)tion of propylene oxide such as in the proportion of 2 to 3 may be usedif desired. Where alcohol is used we prefer to limit the combined totalof the propylene oxide and the alcohol to between to 5% of the amount ofthe refrigerant in the system. Q

Instead of the particular fluorine refrigerant named above,tetrafiuorodichloroethane, methyl; methylene or ethyl chloride, or oneof the other refrigerants mentioned in the Midgeley et a1. ResissuePatent 19,265, may be used. The mineral oil should be as free 'fromcorrosive substances aspossible and of the proper viscositycharacteristics. Instead of the mineral oil lub ricant, other lubricantssuch as synthetic lubricants may be used. v

Instead of the propylene oxide 1,2, the inhibitor may be selected fromthe other epoxy members of this same series which is termed the firstethylene oxide series. This first ethylene oxide series includes inaddition to the propylene oxide 1,2, ethylene oxide, butylene oxide 1,2,butylene oxide 2,3, pentylene oxide 1,2, pentylene oxide 2,3, hexyleneoxide 1,2,,hexylen'e oxide 2,3, and hexylene, oxide 3,4. The inhibitormay also be selected from a second ethylene oxide series of epoxy typema-. terials. This second ethylene oxide series differs from the firstethylene oxide series in that each member contains a'phenyl group. Thissecond ethylene oxide series includes phenyl ethylene oxide, phenylpropylene oxide 1,2, phenyl butyl ene oxide 1,2, phenyl butylene oxide2,3, phenyl pentylene oxide 1,2, phenyl pentylene oxide 2,3, phenylhexylene oxide 1,2, phenyl hexylene oxide 2,3, and phenyl hexylene oxide3,4.

The members of the first and second series all include a single oxygenatom connected to two adjacent carbon atoms. Because of this structurethe member of these two series are all termed epoxy type organic oxides.They have the structural formula where R is a hydrogen atom, a methyl,ethyl,

.butyl, propyl, phenyl or other similar group.

it is to be understood that other forms might be.

adopted, as may come within the scope of. the claims which follow.

What is claimed is as follows:

1. A working fluid for a compressionrefri'gerat ing system consisting ofas its major constituents a halogenated aliphatic hydrocarbonrefrigerant containing not more than two carbon atoms in the moleculeand a mineral oillubricant; and as its minor constituent an organicoxide inhibitor of the epoxy type in an amount equivalent to not morethan 5% of the refrigerant in the system having the following structuralformula,

in which R and R represent a hydrogen atom, a methyl, ethyl, butyl,propyl, phenyl group with the total number of carbon atoms in R and Rexclusive of the phenyl group not exceeding 4.

2. A working fluid for a compression refrigerant system consisting of asits major constituents a halogenated aliphatic hydrocarbon refrigerantcontaining not more than two carbon atoms in the molecule and a mineraloil lubricant, and as its minor constituents mono-hydroxy alcohol havingno more than four carbon atoms in the molecule and an organic oxideinhibitor of the epoxy type having the following structural formula,

in which R and R represent a hydrogen atom, a methyl, ethyl, .butyl,propyl, phenyl group with the total number of carbon atoms in R and R.exclusive of the phenyl group not exceeding 4.

3. The method of refrigeration which consists of liquefying ahalogenated refrigerant in the presence of a mineral oil and an epoxytype organic oxide inhibitor in an amount equivalent .to not more than5% of the refrigerant having the formula set forthin claim 1 hereof, andthereafter evaporating the refrigerant.

4. A workingfiuid fora compression refrigerating system which consistsof as its major constituents a refrigerant fluorochloro derivative of analiphatic hydrocarbon having not more than two carbon atoms to themolecule and a mineral oil lubricant and has as a minor constituentphenyl ethylene oxide as an inhibitor in an amount equivalent to notmore than 5% of the refrigerant.

5. A working fluid for a compression refrigerating system which consistsof as its major constituents a refrigerant fluorochloro derivative of analiphatic hydrocarbon having not more than two carbon atoms to themolecule and a mineral oil lubricant and has as a minor constituentpropylene oxide 1,2, as an inhibitor in an amount equivalent to not morethan 5% of the refrigerant.

6. A working fluid for a compression refrigeratin'g'system whichconsists of as its major constituents a refrigerant fluorochloroderivative of an aliphatic hydrocarbon having not more than two carbonatoms to the molecule and a mineral oil lubricant and has as a. minorconstituent phenyl ethylene oxide as an inhibitor in an amountequivalent to not more than 5% of the refrigerant and a mono-hydroxyalcohol having notmore than four carbon atoms in the molecule.

7 A working fluid for a compression refrigerating system which consistsof as its major constituents a refrigerant fiuorochloro derivative of analiphatic hydrocarbon having not more than two carbon atoms to themolecule and a mineral oil lubricant and has as a minor constituentpropylene oxide 1,2 as an inhibitor in an amount equivalent to not morethan 5% of the refrigerant and a mono-hydroxy alcohol having not morethan four carbon atoms in the molecule.

ALFRED E. BISHOP. STANLEY V. COOK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,040,905 Zellhoefer May 19, 19362,149,947 Zellhoefer Mar. 7, 1939 2,166,604 Meyer July 18, 19392,185,332 Crampton Jan. '2, .1940

OTHER REFERENCES Gregory: Uses and Applications of Chemical and RelatedMaterials, vol. II (1944).. Reinhold Pub. Corp. Page 277.

